@Manual{flatberg09opl,
 title = {A short OPL tutorial},
 author = {Truls Flatberg},
 year = {2009},
 note = {\url{http://folk.uio.no/trulsf/opl/opl_tutorial.pdf}},
}

@manual{gmpl,
    author = {Makhorin, Andrew},
    citeulike-article-id = {5651700},
    keywords = {gmpl},
    month = dec,
    posted-at = {2009-08-26 19:00:17},
    priority = {2},
    title = {{Modeling Language GNU MathProg}},
    year = {2008}
}

@manual{glpk,
    author = {Makhorin, Andrew},
    citeulike-article-id = {5651691},
    keywords = {glpk},
    month = may,
    posted-at = {2009-08-26 18:57:15},
    priority = {2},
    title = {{GNU Linear Programming Kit}},
    year = {2009}
}

@manual{glpkWiki,
    author = {Wikibooks},
    keywords = {glpk},
    title = {GLPK},
    \note = {\url{http://en.wikibooks.org/wiki/GLPK}},
}
